Generally, the widely-used peripheral input device of a computer system includes for example a mouse, a keyboard, a trackball, or the like. Via the keyboard, characters or symbols can be directly inputted into the computer system. As a consequence, most users and most manufacturers of input devices pay attention to the development of keyboards. As known, a keyboard with scissors-type connecting elements is one of the widely-used keyboards.
Hereinafter, a key structure with a scissors-type connecting element of a conventional keyboard will be illustrated with reference to FIG. 1. FIG. 1 is a schematic side cross-sectional view illustrating a conventional key structure. As shown in FIG. 1, the conventional key structure 1 comprises a keycap 11, a scissors-type connecting element 12, a rubbery elastomer 13, a membrane switch circuit member 14 and a base 15. The keycap 11, the scissors-type connecting element 12, the rubbery elastomer 13 and the membrane switch circuit member 14 are supported by the base 15. The scissors-type connecting element 12 is used for connecting the base 15 and the keycap 11.
The scissors-type connecting element 12 is arranged between the base 15 and the keycap 11, and the base 15 and the keycap 11 are connected with each other through the scissors-type connecting element 12. The scissors-type connecting element 12 comprises a first frame 121 and a second frame 122. A first end of the first frame 121 is connected with the keycap 11. A second end of the first frame 121 is connected with the base 15. The rubbery elastomer 13 is enclosed by the scissors-type connecting element 12. The membrane switch circuit member 14 comprises plural key intersections (not shown). When one of the plural key intersections is triggered, a corresponding key signal is generated. The rubbery elastomer 13 is disposed on the membrane switch circuit member 14. Each rubbery elastomer 13 is aligned with a corresponding key intersection. When the rubbery elastomer 13 is depressed, the rubbery elastomer 13 is subjected to deformation to push the corresponding key intersection of the membrane switch circuit member 14. Consequently, the corresponding key signal is generated.
The operations of the conventional key structure 1 in response to the depressing action of the user will be illustrated as follows. Please refer to FIG. 1 again. When the keycap 11 is depressed, the keycap 11 is moved downwardly to push the scissors-type connecting element 12 in response to the depressing force. As the keycap 11 is moved downwardly relative to the base 15, the keycap 11 pushes the corresponding rubbery elastomer 13. At the same time, the rubbery elastomer 13 is subjected to deformation to push the membrane switch circuit member 14 and trigger the corresponding key intersection of the membrane switch circuit member 14. Consequently, the membrane switch circuit member 14 generates a corresponding key signal. When the keycap 11 is no longer depressed by the user, no external force is applied to the keycap 11 and the rubbery elastomer 13 is no longer pushed by the keycap 11. In response to the elasticity of the rubbery elastomer 13, the rubbery elastomer 13 is restored to its original shape to provide an upward elastic restoring force. Consequently, the keycap 11 is returned to its original position where it is not depressed. The structures and the operations of the conventional key structure have been mentioned as above.
With increasing development of science and technology, the demand on a slim-type keyboard is gradually increased. For example, a slim-type keyboard as shown in FIG. 2 is introduced into the market. FIG. 2 is a schematic side cross-sectional view illustrating another conventional key structure. As shown in FIG. 2, the conventional key structure 2 comprises a keycap 21, a scissors-type connecting element 22, a metallic triggering element 23, a membrane switch circuit member 24 and a base 25. The structures and functions of the keycap 21, the scissors-type connecting element 22, the membrane switch circuit member 24 and the base 25 are substantially identical to those of the corresponding components of the key structure 1, and are not redundantly described herein. In comparison with the key structure 1, the key structure 2 comprises the metallic triggering element 23 in replace of the rubbery elastomer 13.
The metallic triggering element 23 is disposed on the membrane switch circuit member 24. When the metallic triggering element 23 is pushed by the keycap 21, the metallic triggering element 23 is subjected to deformation to push the membrane switch circuit member 24. Consequently, a corresponding key signal is generated. When the keycap 21 is no longer depressed by the user, the deformed metallic triggering element 23 is restored to its original shape to provide an upward pushing force. Consequently, the keycap 21 is returned to its original position where it is not depressed. The metallic triggering element 23 is made of a metallic material. Moreover, the thickness of the metallic triggering element 23 is smaller than the thickness of the rubbery elastomer 13. Consequently, the overall thickness of the conventional key structure 2 is smaller than the overall thickness of the conventional key structure 1. Moreover, a pressing part 211 is disposed on an inner surface of the keycap 21 and aligned with the metallic triggering element 23. The pressing part 211 is integrally formed with the keycap 21. Moreover, both of the pressing part 211 and the keycap 21 are made of a plastic material.
However, since the metallic triggering element 23 is made of a metallic material, some problems may occur. For example, when the keycap 21 is depressed by the user, the metallic triggering element 23 made of the metallic material may adversely affect the tactile feel of the keycap 21.
Therefore, there is a need of providing a key structure with slimness and enhanced tactile feel.